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Full text of "The Morphology And Evolution Of The Apes And Man"

LEMUEOIDEA                             23
The liver exhibits many primitive features. It resembles that of many quadrupeds in its tendency to form numerous little lobules, It has deep incisura? for the oesophagus and duodenum. The left lateral lobe is large, the Spigelian lobe is small, and the caudate lobe is large in true Lemurs; the size of the caudate and Spigelian lobes varies in different species. The gall-bladder is sunk in a hollow, and there is a variable amount of contortion of its narrow end and of the common bile duct. The bare area between the liver and the diaphragm is marked.
The Organs of Circulation.—The cardiac apex is formed by both ventricles, whereas it is usually formed by the left ventricle in the higher Primates; in a Drill I observed it formed by the right ventricle (174). And the pericardium only adheres slightly to the diaphragm.
The aortic arch gives off the innominate and left sub-clavian arteries, and the former breaks up into the right subclavian and both common carotid arteries. This arrangement is frequent among lower Mammals, and in the Gibbons and Chimpanzees, but not in the Gorilla nor in Man. Between the heart and diaphragm there lies the fourth lobe of the right lung as in the Carnivora.
The brachial artery divides in the Lorises into an immense number of long parallel branches, constituting a form of rete mirabile. The axillary artery gives off a trunk which divides into the humeral circumflex, scapular circumflex, thoraco-dorsal and subscapular; and a somewhat similar condition in a Chimpanzee is shown in fig. 41. The femoral artery also breaks up into sheafs of vessels in the Lorises. This multiple subdivision of arteries is also met with in the Sloth, Whale,